What Is Hyperbaric Oxygen Therapy?

  • Alexa McguinnessBachelor of Medicine, Bachelor of Surgery, Bachelor of the Art of Obstetrics


Oxygen is necessary for our survival, with every cell in the body relying on it to function. We take oxygen into the body when we inhale which is transported in the bloodstream to the organs.1 Certain conditions can cause a deficiency of oxygen in the blood, known as hypoxemia, such as hiking at high altitudes, deep-water diving, and diseases impacting the lungs, such as emphysema.2 It is difficult for the body to adapt to these situations, so, in such situations, hyperbaric oxygen therapy (HBOT) can come into play.3

During HBOT, a patient inhales pure oxygen whilst enclosed in a pressurised chamber which rapidly increases the supply of oxygen to the blood and organs. Not only can this procedure correct conditions characterised by hypoxemia, but, it can also promote wound healing. Though it can be efficacious, multiple sessions of HBOT may be required. Furthermore, this therapy is not without side effects. Consulting with your physician can help you establish whether HBOT may be suitable for you.3,4,5,6

Indications for hyperbaric oxygen therapy

HBOT can be used to treat a range of conditions characterised by a lack of oxygen in the blood. Furthermore, HBOT may also be utilised to promote wound healing. Some of the key applications of HBOT are discussed below.

Decompression sickness from deep-water diving

Decompression sickness occurs when gas bubbles that form in the body when diving at deep depths, do not have enough time to leave the body, due to a diver rapidly ascending to the surface of the water, resulting in these gas bubbles becoming trapped in parts of the body. Severe pain in the limbs and joints is a characteristic feature of decompression sickness and if untreated can lead to  brain damage and death.8

Carbon monoxide poisoning

Carbon monoxide is a colourless, odourless, and very toxic gas. It leads to decreased oxygen levels in the blood by binding to haemoglobin, the protein that transports oxygen in the blood, so oxygen cannot bind to it. Carbon monoxide poisoning can cause a range of signs and symptoms, from headaches to life-threatening conditions.9

Gas gangrene

Gas gangrene is a rapidly progressing and life-threatening infection of soft tissue.  This very rare infection can be  caused by physical trauma, or less often by advanced cancers, diabetes mellitus, and in those with a weaker immune system.10

Brain injuries

Brain injuries can range largely in their severity, from causing mild changes to consciousness to severe impacts, such as comas and death. Causes of brain injuries can vary, but, physical trauma is a key cause.11 


Wounds are disruptions to the integrity of skin or tissue, and can be simple, where they are confined to the skin, or complicated, where they span across deeper areas, involving injury to blood vessels, nerves, and muscles. Physical trauma, extreme temperatures, chemicals, and radiation can all cause wounds.12

Process of hyperbaric oxygen therapy

Fundamentally, HBOT is the supply of oxygen to a patient at an increased pressure through a chamber. The chamber used in HBOT can either be a monoplace chamber, for one patient, or a multi-place chamber, for multiple patients, that is approximately two to fourteen patients. Monoplace chambers are typically compressed with pure oxygen. In contrast, multiplace chambers contain pressurised air and have tight-fitting masks which can be fitted onto patients so that they receive oxygen. Depending on why the treatment is being used, it can last one and a half to two hours and may be performed multiple times daily. Through these sessions, oxygen in the blood should rise, thus treating conditions characterised by a lack of oxygen.3,4

Contraindications for hyperbaric oxygen therapy

Patients with untreated pneumothorax, that being a collapse of the lung, should not undergo HBOT as this can have life-threatening complications.13

Patients taking certain medications may have to stop taking them when undergoing HBOT, as HBOT may increase the chance of side effects of these medications occurring. Consulting with a physician can help determine whether this may be the case for you.13

Risks of hyperbaric oxygen therapy

HBOT carries several risks. Key among these risks are barotrauma, oxygen toxicity, disorders of the eye, and claustrophobia.14


HBOT involves being exposed to increased pressure.3,4 Barotrauma is an injury that results from increased pressure that leads to the overstretching of tissue. Mostly, barotrauma causes injury to the sinuses, ears, teeth, and lungs. Barotrauma can result in pain, as well as damage to tissues, which carries different consequences depending on the tissue impacted.15

Oxygen toxicity 

During HBOT, patients inhale pure oxygen. Rarely, this can result in oxygen toxicity. This predominantly impacts the central nervous system and lungs. When oxygen toxicity occurs in the central nervous system, this can cause seizures which may be preceded by twitching, auditory hallucinations, changes in vision, nausea, vertigo, anxiety, and irritability. When the lungs are impacted by oxygen toxicity, signs and symptoms can include localised chest pain that worsens when inhaling which can progress to more widespread chest pain, coughing, a sensation of tightness in the chest, and difficulty breathing. Signs and symptoms typically disappear in the days following HBOT.14

Disorders of the eye

Exposure to oxygen during HBOT can impact the eye. Said impact includes myopia or nearsightedness, where objects appear clear when up close but are difficult to see when farther away. Another disorder of the eye, and a potential consequence of HBOT, is cataracts, which cause cloudy vision.14


Undergoing HBOT involves being enclosed in a small space. For those with claustrophobia, that is the fear of being enclosed in small spaces with no escape, HBOT can trigger anxiety. The severity of this anxiety can vary depending on whether someone has mild or severe claustrophobia. Patients with claustrophobia may benefit from treatment from a psychologist or psychiatrist before undergoing HBOT.14


Is hyperbaric oxygen therapy safe?

HBOT is considered to be one of the safest therapies in use. It does, however, carry some potential side effects, namely, barotrauma, oxygen toxicity, disorders of the eye, and claustrophobia.14

How long does a typical hyperbaric oxygen therapy last?

A session of HBOT typically lasts one and a half to two hours. These sessions can take place up to three times a day and patients may undergo multiple days of therapy.3

Are there any contraindications to hyperbaric oxygen therapy?

Patients who have an untreated collapsed lung, known as pneumothorax, should not undergo HBOT as this may be life-threatening. Furthermore, HBOT may increase the likelihood of certain medications’ side effects occurring, and, therefore, it is important to talk to a physician about the medications you are currently taking before undergoing HBOT.13

Can infants and children receive hyperbaric oxygen therapy?

HBOT can be used in infants and children.16

Can hyperbaric oxygen therapy help with athletic performance and recovery?

Some studies have indicated that HBOT may help athletes recover from injuries faster and can also be helpful for athletes in recovering from bodily fatigue, as well as enhance athletic performance.17,18,19 However, other research has suggested that the impact of HBOT on athletic performance and recovery is insignificant. More studies on the matter, taking into account different types of athletic activity and whether HBOT is provided before, during, or after exercise, may need to be conducted to form a more conclusive idea of HBOT’s impact on athletic performance and recovery.20,21


Hyperbaric oxygen therapy (HBOT) is a treatment used to increase oxygen in the blood, and subsequently in tissues, in cases where levels of oxygen are low, such as when at high altitudes, at deep depths in water, and in certain conditions of the lung. HBOT can also be used to promote wound healing. HBOT can involve one chamber for a single patient or multiple chambers for many patients to use, with sessions ranging from one and a half to two hours, and many sessions potentially being needed to treat a condition. HBOT is considered to be among the safest therapies, though it can carry side effects, including barotrauma, oxygen toxicity, disorders of the eye, and claustrophobia.


  1. Arora S, Tantia P. Physiology of oxygen transport and its determinants in intensive care unit. Indian Journal of Critical Care Medicine.2019; 23(3): 172-177. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785823/ 
  2. Trayhurn P. Oxygen: the forgotten nutrient. Journal of Nutritional Science. 2017; 6: e47. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5672318/ 
  3. Ortega MA, et al. A general overview on the hyperbaric oxygen therapy: applications, mechanisms and translational opportunities. Medicina. 2021; 57(9): 864. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8465921/ 
  4. Thom SR. Hyperbaric oxygen: its mechanisms and efficacy. Plastic and Reconstructive Surgery. 2012; 127(1): 131-141. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3058327/ 
  5. Heyboer M. Hyperbaric oxygen therapy side effects: where do we stand? Journal of American College of Clinical Wound Specialists. 2016; 8(1-3): 2-3. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6161636/ 
  6. Cave E. Selecting treatment options and choosing between them: delineating patient and professional autonomy in shared decision-making. Health Care Analysis. Health Care Analysis. 2020; 28(1): 4-24. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7045795/ 
  7. Sen S, Sen S. Therapeutic effects of hyperbaric oxygen: integrated review. Medical Gas Research. 2-21; 11(1): 30-33. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8103971/ 
  8. Hall J. The risks of scuba diving: a focus on decompression illness. Hawai’i Journal of Medicine and Public Health. 2014; 73(11): 13-16. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4244896/ 
  9. Chenoweth JA, Albertson TE, Greer MR. Carbon monoxide poisoning. 2021; 37(3): 657-672. Critical Care Clinics. Available from: https://pubmed.ncbi.nlm.nih.gov/34053712/ 
  10. Lee H, et al. A fatal spontaneous gas gangrene due to Clostridium perfringens during neutropenia of allogeneic stem cell transplantation: case report and literature review. Infection and Chemotherapy. 2014; 46(3): 199-203. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4189134/ 
  11. Galgano M, et al. Traumatic brain injury: current treatment strategies and future endeavors. Cell Transplantation. 2017; 26(7): 1118-1130. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657730/ 
  12. Kujath P, Michelsen A. Wounds: from physiology to wound dressing. Deutsches Ärzteblatt International. 2008; 105(13): 239-248. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2696775/ 
  13. Gawdi R, Cooper JS. Hyperbaric contraindications. StatPearls [Internet]. 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557661/ 
  14. Heyboer M, Sharma D, Santiago W, McCulloch N. Hyperbaric oxygen therapy: side effects defined and quantified. Advances in Wound Care. 2017; 6(6): 210-224. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5467109/ 
  15. Battis AS, Haftel A, Murphy-Lavoie HM. Barotrauma. StatPearls [Internet]. 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482348/ 
  16. Siewiera J, Mews J, Królikowska K, Kalicki B, Jobs K. Hyperbaric oxygenation in pediatrics: indications in the light of evidence-based medicine. Journal of Mother and Child. 2019; 23(2): 142-148. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8522372/ 
  17. Ishii Y, et al. Hyperbaric oxygen as an adjuvant for athletes. Sports Medicine. 2005; 35(9): 739-746. Available from: https://pubmed.ncbi.nlm.nih.gov/16138784/ 
  18. Barata P, Cervaens M, Resende R, Camacho Ó, Marques F. Hyperbaric oxygen effects on sports injuries. Therapeutic Advances in Musculoskeletal Disease. 2011; 3(2): 111-121. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3382683/ 
  19. Hadanny A, et al. Effects of hyperbaric oxygen therapy on mitochondrial respiration and physical performance in middle-aged athletes: a blinded, randomized controlled trial. Sports Medicine Open. 2022; 8: 22. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8825926/ 
  20. Branco BHM, et al. The effects of hyperbaric oxygen therapy on post-training recovery in jiu-jitsu athletes. Plos One. 2016; 11(3): e0150517. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4784886/ 
  21. Huang X, Wang R, Zhang Z, Wang G, Gao B. Effects of pre-, post-, and intra-exercise hyperbaric oxygen therapy on performance and recovery: a systematic review and meta-analysis. Frontiers in Physiology. 2021; 12: 791872. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8650584/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Alexa McGuinness

Bachelor of Medicine, Bachelor of Surgery, Bachelor of the Art of Obstetrics, Royal College of Surgeons in Ireland

Alexa is a medical student at the Royal College of Surgeons in Ireland, passionate about healthcare and the role medical research and medical writing plays in optimizing this. She has experience aiding research on public health policy. She also is engaged in medical research, as well as medical writing, including here, at Klarity.

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